A graphical user interface (GUI) is a type of user interface through which users can interact with a machine, by visualization and manipulation of elements on the user interface, such as graphical icons. For a user to interact with a GUI, interface devices are used, including a computer keyboard or cursor control devices, such as a computer mouse or touchpad. One such object that can be manipulated in the GUI, with an interface device, is a scroll bar. A scroll bar is a horizontal or vertical bar in a GUI that allows a user to move the viewing area of content, such as text or images that span more than one viewing window.
One example of a software application that makes use of scroll bars is a web browser. When using a web browser, users will often open two or more interfaces at the same time in order to view content from multiple sources simultaneously. One method of displaying multiple interfaces is through the use of panels. A panel is a particular arrangement of information grouped together for presentation to users within a window. The ability to display multiple panels and use a scroll bar to move through the content of the panels may be highly desirable to users, as this can increase usability and functionality for the user.